Xem Studiomeasured geometry

Library › Joinery › Japanese joinery ·

Koshikake ari tsugi (lapped dovetail splice)

What is a koshikake ari tsugi joint? · Hardware · basis: Xem Studio design — geometry computed in the generator from traditional proportions

Also called: koshikake ari tsugi, 腰掛蟻継ぎ, lapped dovetail splice, japanese beam splice, seated dovetail splice, empalme japonés cola de milano con asiento, japanischer Balkenstoß

Exact dimensions. True size, with no printing tolerance added.

length
130.0 mm
width
20.0 mm
height
20.0 mm

Notes

  • Woodworking joint drawn for 3D printing: the parts lock together by shape, so a print can be joined without glue or screws. Drawn at true size with the parts line to line (zero gap) in their assembled position — add your printer's fit allowance to the mating faces (your AI or slicer can do this).
  • The dovetail splice with a seat (koshikake): the female member's lower part runs under the tenon and carries the male member's load — the most common sill and beam splice in Japanese carpentry.

Koshikake ari tsugi size chart

dimensionvalue
stock20 × 20 mm square
partsmale, female
dovetail8 → 13 mm, 15 mm long, upper 14 mm
seat (koshikake)6 mm thick ledge under the tenon
assemblesthe male drops in from above onto the seat
holdspulling apart lengthwise; the seat carries load downward

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Xem StudioJoinery design (geometry computed in the generator from traditional proportions)webXem Studio design

Free files

★ Free files 3 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

koshikake-ari-tsugi-lapped-dovetail-splice-maleMale member: dovetail tenon in the upper 14 mmSTEP · STL
koshikake-ari-tsugi-lapped-dovetail-splice-femaleFemale member: dovetail socket plus the 6 mm seat it rests onSTEP · STL
koshikake-ari-tsugi-lapped-dovetail-splice-assembledAll parts in their assembled position (each part its own solid)STEP · STL
Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=koshikake-ari-tsugi-lapped-dovetail-splice

Koshikake ari tsugi (lapped dovetail splice), isometric render of a generated part
Render of koshikake-ari-tsugi-lapped-dovetail-splice-assembled from the free STEP; not to scale.

Fits with

Ari tsugi (Japanese dovetail splice), isometric render of a generated part
Ari tsugi (Japanese dovetail splice)130.0×20.0×20.0 mm★ 3 files
Koshikake kama tsugi (lapped gooseneck splice), isometric render of a generated part
Koshikake kama tsugi (lapped gooseneck splice)130.0×20.0×20.0 mm★ 3 files

Questions

What is the koshikake?

The seat: a ledge on the female member that the male member's dovetail rests on.